The present invention relates to two beam photometers and more particularly to improvements in the construction of such photometers.
Two beam photometers include, for example, a single light source and means to establish two beams, one to serve as measuring beam, the other one as reference beam. Light source and beam paths are, for example, included in a block with V-shaped ducts of equal lengths, wherein the bottom of the V defines the location of the source, and the duct ends (ends of the legs of the V) are closed physically by means of windows. Moreover, a rotating shutter diaphragm is disposed in the block for rotation so as to intercept both beams. The shutter disk or diaphragm is seated on a shaft which traverses the block and extends from a motor which, in turn, is affixed to the block.
German printed patent application 2,052,609, and corresponding U.S. Pat. No. 3,715,153, issued to Schunck et al, describes a particularly shaped rotating shutter with excentric disposition in relation to the exit windows of such a block.